Answer:

1. 3a, 4b, 5c, 6d, 7e, 8f

2. z, 2z, 3z, 4z, 5z, 6z, 7z

3. a + b, a + 3b, a + 5b, a + 7b, a + 9b, a + 11b

4. f + g, 2f + 2g, 3f + 3g, 4f + 4g, 5f + 5g, 6f + 6g

5. x + 2y, X + 4y, x + 6y, x + 8y, x + 10y, x + 12y